We present a comprehensive framework for interpreting electron recoil signals induced by fast-moving dark matter (DM), applicable across a wide range of theoretically motivated models. Amid both null results in conventional weakly interacting massive particle searches and growing interest in alternative DM scenarios, we focus on (semi-)relativistic DM components that can arise from mechanisms such as DM annihilation, decay, or cosmic-ray acceleration. These boosted DM candidates produce distinct experimental signatures that differ qualitatively from nonrelativistic DM, necessitating a dedicated treatment. Our framework incorporates relativistic kinematics and atomic effects through ionization form factors, enabling accurate predictions of differential cross sections in both low- and high-energy regimes. We demonstrate how atomic effects become negligible at high recoil energies, validating the free-electron approximation in specific parameter regions. Furthermore, we highlight the complementarity between low-threshold direct detection experiments and high-threshold neutrino observatories in probing fast-moving DM across broad kinematic domains. This formalism provides a robust and model-independent foundation for interpreting current and future searches for relativistic DM.

We investigate the $B-L$ gauge extension of the Standard Model that the Dirac seesaw mechanism with thermal leptogenesis leaves imprints in the early Universe via the stochastic gravitational background emanating from a network of cosmic strings when $B-L$ symmetry is broken. With right-handed neutrino mass lighter than the typical scale of grand unification, the $B-L$ symmetry protecting the right-handed neutrinos leads to constraints on the Yukawa couplings for both Dirac and Majorana scenarios. Estimating the predicted gravitational wave background we find that future space-borne missions could probe the range concerning thermal Dirac leptogenesis. In a comparative analysis between such probes of gravitational waves sourced from cosmic strings in Dirac and Majorana leptogenesis in the $B-L$ extension, based on the energy scales of the leptogenesis, for instance, gravitational waves detectors will be able to probe the scale of Dirac leptogenesis up to ${10}^9\mathrm{GeV}$, while for Majorana leptogenesis it would be upto ${10}^{12}\mathrm{GeV}$.

Nucleon elastic electromagnetic form factors obtained using both the three-body and $\mathrm{quark}+\text{fully}$ interacting-diquark pictures of nucleon structure are employed to calculate an array of light-front transverse densities for the proton and neutron and their dressed valence-quark constituents, viz. flavor separations of the proton and neutron results. These two complementary descriptions of nucleon structure deliver mutually compatible predictions, which match expectations based on modern parametrizations of available data, where such are available. Among other things, it is found that transverse-plane valence $u$- and $d$-quark Dirac radii are practically indistinguishable; but regarding kindred Pauli radii, the $d$ quark value is roughly 10% greater than that of the $u$-quark. Moreover, magnetically, the valence $d$ quark is far more active than the valence $u$ quark, probably because it has much greater orbital angular momentum. Both pictures of nucleon structure agree in predicting that, in a polarized nucleon, the transverse-plane charge densities are no longer rotationally invariant. Instead, for a $+\widehat{x}$ polarized nucleon, positive charge is displaced in the $+\widehat{y}$ direction, with the opposite effect for negative charge.

In this work, we perform a comprehensive investigation of the production of high-spin ${\omega }_J$ and ${\rho }_J$ mesons ($J=2$, 3, 4, 5) in ${\pi }^{-}p$ reactions using an effective Lagrangian approach. By constructing the relevant $t$-channel processes and calibrating the model with a single adjustable parameter fitted to existing data, we successfully reproduce the measured total and differential cross sections for the $J=3$ states ${\omega }_3(1670)$ and ${\rho }_3(1690)$. Within the same framework, we predict the production cross sections for their lower- and higher-spin partners; ${\omega }_2(1975)$, ${\rho }_2(1940)$, ${\omega }_4(2250)$, ${\rho }_4(2230)$, ${\omega }_5(2350)$, and ${\rho }_5(2350)$. Our results show that these states exhibit measurable cross sections with characteristically forward-peaked angular distributions, underscoring their strong potential for observation in future $\pi p$ meson-beam experiments.

In a recent work [B. J. P. Jones and J. A. Formaggio, Phys. Rev. Lett. 135, 111801 (2025)], the possibility of superradiant neutrino emission from atomic condensates has been theoretically proposed. Subsequent analysis by Y. K. Lu, H. Lin, and W. Ketterle [arXiv:2510.21705] questioned this scenario, emphasizing the limiting role of the fermionic nature of the decayed atoms. In this study, we revisit the problem and discuss under which conditions collective emission phenomena might still emerge in cold-atom systems.

The dark photon is a well motivated candidate for the dark matter that comprises most of the mass of our visible Universe, leading to worldwide experimental and observational efforts toward its discovery. A primary tool in this search is the cavity haloscope, which facilitates resonantly enhanced conversion to photons from both dark photons and axions. In this context, limits from axion search experiments are often directly converted into dark photon constraints, without re-analyzing the original data. However, this rescaling may not fully capture all of the relevant physics due to various reasons. By reexamining data taken by the Taiwan Axion Search Experiment with Haloscope experiment, we derive a world-leading constraint on the dark photon parameter space, excluding $|\epsilon |\gtrsim 2\times {10}^{-14}$ in the $19.46–19.84\mathrm{\mu }\mathrm{eV}$ mass range, which exceeds the naïve “rescaling limit” by roughly a factor of two. We emphasize that accounting for the scanning timing information is crucial for deriving limits for the polarized dark photon case. In the data, we also analyze a tentative signal excess with a local significance of $4.7\sigma$ ($m_X\simeq 19.5\mathrm{\mu }\mathrm{eV}$) that persists in the absence of a magnetic field. While this excess mimics the behavior of a dark photon signal, it has been excluded by recent results from the HAYSTAC and ORGAN-Q experiments. This case study, nevertheless, highlights the risk of discarding valid dark photon signals when relying on axion-specific magnetic field vetoes.

The binary black hole signal GW250114, the clearest gravitational wave detected to date, offers a unique opportunity to test general relativity in the relativistic strong-gravity regime. How well does GW250114 agree with Einstein’s predictions in the plunge-merger-ringdown stage? To address this point, we constrain deviations from general relativity across the plunge-merger-ringdown stage of spin-precessing binaries with a parametrized waveform model within the effective-one-body formalism. We find that deviations from the peak gravitational-wave amplitude and instantaneous frequency of the $(\ell ,|m|)=(2,2)$ mode are constrained to about 10% and 4%, respectively, at 90% credible level. These constraints are, respectively, 2 and 4 times more stringent than those obtained by analyzing GW150914. We also constrain, for the first time, the instantaneous frequency of the $(\ell ,|m|)=(4,4)$ mode at merger to about 6% and the time at which the gravitational-wave amplitude peaks to about 5 ms. These results provide exquisitely precise tests of general relativity in the strong-gravity regime and can be employed to constrain extensions of Einstein’s theory.

Perturbative calculations of gravitational radiation near the horizons of rotating black holes in the frequency domain have been plagued by divergence issues. We resolve this longstanding obstacle by constructing a nonsingular source term for near-horizon gravitational perturbations, or equivalently perturbed Weyl scalars ${\psi }_0$ with a spin weight of $s=+2$, within the generalized Sasaki-Nakamura formalism for the first time. As illustrative applications, we compute the dynamical deformation of the event horizon induced by an ultrarelativistic particle plunge, demonstrating the excitation of quasinormal modes at the horizon, and we evaluate the energy flux toward the horizon from an extreme mass-ratio inspiral. This work provides a powerful tool for studying physics near black hole horizons.

We show that the threshold to form a black hole, in an asymptotically flat and radiation-dominated Friedman-Robertson-Walker (FRW) Universe, is not solely (mainly) determined by the behavior of the compaction function at its extrema, as earlier thought, but also by the Ricci scalar of the spatial geometry at smaller (but superhorizon) scales, which we call “the core.” We introduce three classes of initial conditions characterized by an open (O), closed (C), or flat (F) FRW core surrounded by a shell with higher three-dimensional curvature. In the C case, the core helps the collapse so that the black hole formation threshold is the lowest among all cases. Type-II black holes might only be generated by type O or F (each of those with different thresholds, with O being the highest) or by a type C with a negligible Ricci scalar at the center, which we call an effective F core. Finally, we argue that an F core is typically more probable for a sharp power spectrum; however, it is also more likely related to nonspherical initial conditions. On the other hand, a very broad power spectrum, which might be related to the observed NanoGrav signal, would favor the formation of type-I black holes with a mass spectrum peaked at the infrared scale.

We investigate reversible and irreversible thermodynamic processes in cosmology and their impact on the Hubble tension through modifications to early and late-time expansion history. Gravitationally induced adiabatic matter creation/annihilation are treated as irreversible processes, while energy exchange between the cosmic bulk and horizon is modeled as reversible. We propose two thermodynamically interacting scenarios: Model I considers matter creation/annihilation across all species with energy transfer to effective entropic dark energy, while model II focuses on dark matter creation/annihilation with energy flow from baryonic matter and radiation. Both incorporate the generalized first law of thermodynamics with matter creation/annihilation governed by $\mathrm{\Gamma }(t)={\mathrm{\Gamma }}_{0}H$ and energy transfer quantified by parameter $\gamma$. We perform observational analysis using $\mathrm{Pantheon}+$, cosmic microwave background distance priors, baryon acoustic oscillations, gamma-ray bursts, cosmic chronometers, with and without SH0ES measurements. When SH0ES data are included, matter annihilation scenarios (${\mathrm{\Gamma }}_0<0$) become statistically preferred, yielding $H_0=71.75\pm 0.79\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ (model I) and $H_0=71.06\pm 0.81\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ (model II), achieving $1.2\sigma$ and $1.8\sigma$ agreement with the SH0ES measurement of $H_0=73.17\pm 0.86\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$. Matter creation (${\mathrm{\Gamma }}_0>0$) or pure energy flow [$\mathrm{\Gamma }(t)=0$] scenarios show no such improvement. However, without SH0ES data, information criteria show no preference for the thermodynamically interacting models over $\mathrm{\Lambda }\mathrm{CDM}$, indicating the models’ performance depends critically on local distance ladder calibration. For matter annihilation scenarios with energy flow, effective entropic dark energy exhibits dynamical evolution, mimicking radiation and matter before recombination, then transitioning through quintessence toward the cosmological constant today. These results demonstrate that thermodynamically motivated interactions provide a theoretically consistent framework that accommodates tension alleviation when calibrated with SH0ES measurements, while highlighting the broader challenge of reconciling early-universe and local observational constraints.

The first all-sky-all-frequency (ASAF) radiometer search was conducted using data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. The significance of this search lies in its fast and unmodeled approach, leveraging a cross-correlation technique to identify common signals across the detector network. As a result, this method serves as an excellent alternative to search for unknown or poorly modeled continuous wave sources and narrow band components of the gravitational wave (GW) background. For continuous wave sources whose waveform can be modeled, this method can serve as the first stage of a hierarchical scheme by identifying subthreshold candidates to be followed up with more optimal but computationally expensive searches. The ASAF search, however, presently suffers from beam smearing, where multiple candidates may arise due to the same noise fluctuations, detector artifact, or a GW source. This can reduce the detection probability in follow-up analyses, especially with limited computing resources. To mitigate this issue and reduce the number of correlated and unnecessary candidates, we introduce a novel peak finder algorithm. This algorithm helps identify the most representative candidates while preserving detection sensitivity, thereby allowing follow-up of a much larger number of independent candidates. This reduction in correlated samples leads to a significant reduction in the number of trial factors and also the false dismissal rate (FDR), depending upon the frequency, strength of the injected signal, and the number of candidates, $N$, that can be followed up, with the reduction in FDR being most significant at low frequencies, and small $N$. For instance, at 30 Hz, following up $N=2$ peak finder candidates reduces FDR by a factor of $\sim 3$. At high $N$, the peak finder FDR is higher than the full sky FDR. However, this is of no practical consequence as we can only follow up a small number of candidates per frequency bin.

It is demonstrated that, within the eikonal approach, the Coulomb corrections to the elastic electromagnetic nonflip and spin-flip proton-nucleus amplitudes are identical when the two amplitudes share the same exponential form factors. This result allows Coulomb corrections to be computed numerically, and with high precision, for both electromagnetic and hadronic elastic $p^{\uparrow }A$ amplitudes in the massless-photon limit, including the effects of soft magnetic photon exchange. The method relies on analytical expressions and numerical integrations over a finite impact-parameter range with nonsingular integrands, providing a practical and systematically controlled framework for phenomenological applications.

The origin of the Higgs boson ($H_{125}$), discovered in 2012, remains a mystery. In the metric affine theory (MAT) framework, we study the scalar potential and investigate a couple of scenarios for the symmetry breaking mechanisms with a dilaton model which is derived from the geometry. The LHC constraints for the couplings of Yukawa couplings, Higgs-weak vector bosons and Higgs self-couplings, in this model are examined, which identify the parameter space where the discovered Higgs boson $m_h=125\mathrm{GeV}$ can be dilaton-dominant and the features of Higgs self-couplings are explored. It is found that via the measurements of Higgs pair production, the High Luminosity LHC (HL-LHC) running can either confirm or rule out the dilaton dominance.

We present an analysis of parton distribution functions (PDFs) of the proton using Markov chain Monte Carlo (MCMC) methods. The MCMC approach naturally implements Bayes’ theorem and, thus, provides a means to directly sample the underlying probability distribution—in this case, the probability distribution of the PDF parameters. This allows for a straightforward propagation of the resulting uncertainties into any PDF-dependent observable, preserving their simple probabilistic interpretation. In our analysis we include a broad set of deep inelastic scattering data from HERA, BCDMS and NMC experiments along with the Drell-Yan, $W$ and $Z$ boson data from LHC and Tevatron experiments, which combined with theoretical calculations at next-to-next-to-leading order in QCD allow for realistic determination of PDFs. The main focus of this analysis is to explore alternative methods for PDF uncertainty estimation that are more firmly grounded in statistical principles. We show that the flexibility of the Bayes framework, allowing one, e.g., to account for non-Gaussianity or inconsistencies of datasets, is crucial to extract realistic uncertainties when such assumptions are not fulfilled. We also demonstrate that MCMC allows one to determine the $\mathrm{\Delta }{\chi }^2$ value corresponding to a given confidence level in the sample, which can, in turn, be used as a statistically well-founded tolerance criterion used in the Hessian method, thus addressing one of its main long-standing drawbacks.

The near-threshold photo- and electroproduction of heavy vector quarkonia off the proton provides direct access to its gluonic structure. In particular, the cross section for $J/\mathrm{\Psi }$ photoproduction near threshold is governed by the proton’s gluon gravitational form factors (GFFs). In this work, we employ the leading-order generalized parton distribution framework, together with gluon GFFs calculated in a light-front gluon-spectator model inspired by soft-wall AdS/QCD to predict both the differential and total cross sections for near-threshold $J/\mathrm{\Psi }$ and $\mathrm{\Upsilon }$ photoproduction. Our results for $J/\psi$ photoproduction show good agreement with the low-momentum-transfer data from the $J/\psi \text{−}007$ experiment and the GlueX Collaboration at Jefferson Lab. However, at large momentum transfer, the next-to-leading order QCD effects are necessary to describe the data.

We apply the light-cone QCD sum rules with chiral currents to compute transition form factors of the semileptonic decay of the charmed and bottom scalar mesons $D/B$ to $a_0(980)l^{+}{\nu }_l$ $(l=e,\mu )$, where the scalar meson $a_0(980)$ are firstly regarded as two quark states, and contributions from the tetraquark component are then added via proper modulation of four distribution amplitudes considered. The obtained transition form factors and branching fraction are free of the contribution from the light-cone distribution amplitudes at the level of twist-three and two simple relations connecting their form factors are obtained. Our computations indicates that the decay branch fractions are on the margin of the measurements reported by the Beijing Spectrometer III in the pure two-quark scenario and are in good agreement with observations when tetraquark component is considered.

Based on a sample of $(10087\pm 44)\times {10}^{6}J/\psi$ events collected with the BESIII detector, a partial-wave analysis of $J/\psi \to \mathrm{\Lambda }{\overline{\mathrm{\Sigma }}}^0\eta +\mathrm{c}.\mathrm{c}.$ is performed for the first time. The dominant contributions are found to be excited $\mathrm{\Lambda }$ states with $J^P=1/2^{-}$ and $J^P=1/2^{+}$ in the $\eta \mathrm{\Lambda }$ mass spectra. The measured masses and widths are $M=1668.8\pm 3.1\pm 21.2\mathrm{MeV}/c^2$ and $\mathrm{\Gamma }=52.7\pm 4.2\pm 17.8\mathrm{MeV}$ for the $\mathrm{\Lambda }(1670)$, and $M=1881.5\pm 16.5\pm 20.3\mathrm{MeV}/c^2$ and $\mathrm{\Gamma }=82.4\pm 18.2\pm 8.9\mathrm{MeV}$ for the $\mathrm{\Lambda }(1810)$, respectively. The branching fraction is determined to be $\mathcal{B}(J/\psi \to \mathrm{\Lambda }{\overline{\mathrm{\Sigma }}}^0\eta +\mathrm{c}.\mathrm{c}.)=(3.44\pm 0.11\pm 0.13)\times {10}^{-5}$. The first uncertainties are statistical and the second systematic.

Determining the weak charge form factor, $F_W(Q^2)$, of nuclei over a continuous range of momentum transfers, $0\lesssim Q^2\lesssim 0.1{\mathrm{GeV}}^2$, is essential for mapping out the distribution of neutrons in nuclei. The neutron density distribution has significant implications for a broad range of areas, including studies of nuclear structure, neutron stars, and physics beyond the Standard Model. Currently, our knowledge of $F_W(Q^2)$ comes primarily from fixed target experiments that measure the parity-violating asymmetry in coherent elastic electron-ion scattering. Fixed target experiments, such as CREX and PREX-1,2, have provided high-precision weak charge form factor extractions for the ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ nuclei, respectively. However, a major limitation of fixed target experiments is that they each provide data only at a single value of $Q^2$. With the proposed electron-ion collider (EIC) on the horizon, we explore its potential to impact the determination of the weak charge form factor. While it cannot compete with the precision of fixed target experiments, it can provide data over a wide and continuous range of $Q^2$ values, and for a wide variety of nuclei. We show that with data corresponding to an integrated luminosity of $\mathcal{L}\sim 500/A{\mathrm{fb}}^{-1}$, where $A$ is the nucleus atomic weight, the EIC can significantly impact constraints by lifting degeneracies in theoretical models of the neutron density distribution. Ensuring EIC detector coverage at low $Q^2$ and large negative pseudorapidities will be essential for such $F_W(Q^2)$ measurements.

The out-of-equilibrium dynamics of the Sachdev-Ye-Kitaev model (SYK), comprising $N$ Majoranas with random all-to-all four-body interactions, minimally coupled to a Markovian bath modeled by the Lindblad formalism, displays intriguing nontrivial features. In particular, the decay rate toward the steady state is a nonmonotonic function of the bath coupling $\mu$, and the return probability undergoes a first-order dynamical phase transition that eventually becomes a crossover for sufficiently large $\mu$. We provide evidence that these features are closely associated with exceptional point–induced restructuring of the low-energy spectrum of the SYK Liouvillian, in particular those eigenvalues closest to the zero mode corresponding with the steady state. An analytic calculation at small $N$, supported by numerical results for larger $N$, reveals that the value of $\mu \sim 0.1$ at which the exceptional point corresponding to the longest living modes occurs is close to a local maximum of the decay rate. This value marks the start of a region of anomalous equilibration where the relaxation rate diminishes as the coupling to the bath becomes stronger. Moreover, the mentioned change from transition to crossover in the return probability occurs at a larger $\mu \sim 0.3$, corresponding to an increasing density of exceptional point–induced real eigenvalues in the low-energy sector of the Liouvillian spectrum. We expect these features to be generic in the approach to equilibrium in quantum strongly interacting many-body Liouvillians.

Cartan geometry provides a unifying algebraic construction of curvature and torsion, based on an underlying model Lie algebra; a viewpoint that can be extended naturally to the higher algebraic structures underlying supergravity. We present a Cartan-geometric framework for generalized geometries governed by a differential graded Lie algebra, extending previous results. The extended tangent bundle admits the action of both a global duality group $\mathcal{G}$ and a local gauge group $H$. This algebraic structure is implemented via a brane current algebra; the phase space Poisson structure of $p$-branes. Within this Cartan-inspired framework, we define a hierarchy of generalized connections and compute their linearized torsion and curvature tensors, including the higher curvatures required by the tensor hierarchy. This provides a systematic construction of curvature and torsion tensors in generic generalized geometries.